Display research collision warning system

ABSTRACT

A head-up display for a PWI system is disclosed. The display consists of a plurality of strips of an electroluminescent tape secured above and below the windshield and above side windows of a cockpit. The strips are associated with elevation range and azimuth range sectors which are viewable by the pilot through the windshield or windows, and are located in the directions of these sectors. When a target is detected in any of the sectors by a corresponding detector the strip or strips associated with the particular sector are illuminated. The pilot&#39;&#39;s peripheral vision is sufficient to notice their illumination thereby enabling him to directly view the particular sector without reference to a display on the instrument panel.

United States Patent Fletcher et al.

[451 Oct. 17,1972

[S4] DISPLAY RESEARCH COLLISION WARNING SYSTEM [22] Filed: June 25, 1971[2]] Appl. No.: 156,724

521 US. Cl. ..340/27 NA, 340/33, 340/97, 343/112 CA 51 Int. Cl. ..G08g5/00 [58] Field of Search ..73/l78 R; 240/7.7; 340/1 T, 340/16 R, 27 NA,31 R, 33, 34, 97; 343/112 3,052,882 9/1962 Pidhayny ..343/1 12 CA3,321,758 5/1967 Elliot ..343/1 12 CA OTHER PUBLICATIONS Aviation WeekMagazine Sept. 26, 1952, Collins Radar Cocoon to Protect Aircraft,Philip J. Klass, Pp. 37 & 38.

Primary Examiner-Ralph D. Blakeslee Attorney-John R. Manning et al.

[57] ABSTRACT A head-up display for a PWl system is disclosed. Thedisplay consists of a plurality of strips of an electroluminescent tapesecured above and below the windshield and above side windows of acockpit. The strips are associated with elevation range and azimuthrange sectors which are viewable by the pilot through the windshield orwindows, and are located in the directions of these sectors. When atarget is detected in any of the sectors by a corresponding detector thestrip or strips associated with the particular sector are illuminated.The pilots peripheral vision is sufficient to notice their illuminationthereby enabling him to CA directly view the particular sector withoutreference to a display on the instrument panel. [56] References CitedUNITED STATES PATENTS 6 Claims, 4 Drawing Figures 2.560.265 7/1951 Adler..343/l12 CA 3 :2: f 5 7 L2 9 lo PATENTEDUCT 17 I972 SHEET 1 OF 2 FIG.

RENWICK E CURRY LAWRENCE R YOUNG THOMAS BASIL SMITH =l|l JOHN RAWSONHATFIELD INVENTORS B D W. D m H D D 7 8 D D 4 5 D D 2 D D BYWKWATTORNEYS PATENTEDUBT 17 1972 SHEET 2 BF 2 FIG. 4

GI Ll G4 L4 22 K 2 G d/La 5 2 lo |o POWER 30 SOURCE RENICK E. CURRYLAWRENCE R. YOUNG THOMAS BASIL SMITH lll JOHN RAWSON HATFIELD INVENTORSWWzKW ATTORNEYS DISPLAY RESEARCH COLLISION WARNING SYSTEM ORIGIN OFINVENTION The invention described herein was made in the performance ofwork under a NASA contract and is subject to the provisions of Section305 of the National Aeronautics and Space Act of 1958, Public Law 85-568(72 Stat. 435; 42 USC 2457).

BACKGROUND OF THE INVENTION 1. Field of the Invention The presentinvention generally relates to airborne instrumentation and, moreparticularly, to a novel display for use in a pilot warning instrument(PWI) system.

2. Description of the Prior Art The work load of the pilot of todaystraffic environment is increasing, regardless of the polots rating orthe aircraft that he is flying. This is especially true in high densitytraffic areas where the tasks of maintaining vigilance for otheraircraft, performing navigation functions, and following instructionsfrom air traffic controllers create a heavy load on the pilots abilityto fly his aircraft in a safe manner. To prevent mid-air collisions twobasic classes of onboard systems have been developed to assist the pilotto locate the positions of nearby airplanes, hereafter referred to astargets. One class of systems is generally known as the PWI system, forpilot warning indicator, or proximity warning indicator. One infraredPWI system uses currently available xenon strobe lights as atransmitting source. The receivers are built around silicon detectors.The detectors are arrayed so as to provide target position informationfrom selected sectors such as those viewable by the pilot through theairplane's front window or windshield and the two side windows. When atarget is detected in any of the sectors by one of the detectors, theappropriate detector provides an output which is then communicated tothe pilot who has to visually locate the target in the particularsector.

Although a PWI system does not provide target range or target range-ratedata, it does provide bearing and elevation information above thetarget, which has been found to be helpful in locating the target andthereby avoiding mid-air collisions. However, for a PWI system to beeffective it is very important that the information output of thesystem, i.e., the output of any of the detectors, be transmitted to thepilot in a way that enables him to locate the target as soon as possiblewithout ambiguity, and without appreciably impairing his performance incontrolling his aircraft. A PWI system is intended primarily for useunder VFR conditions, i.e., under conditions in which the pilotsattention is directed primarily outside the cockpit. Thus, for the PWIsystem to be effective it is necessary to display the output of thesystem to the pilot without diverting his attention, to a display on theinstrument panel. None of the prior art PWI systems displays theinformation output in such a manner. Therefore, the effectiveness ofprior art PWI systems is unnecessarily limited.

QBJECTS AND SUMMARY OF THE INVENTION It is a primary object of thepresent invention to provide a new improved PWI system.

It is another object of the present invention to provide an improveddisplay arrangement for the output of a PWI system.

A further object of the present invention is to provide a new improveddisplay unit for use in a PWI system which enables the pilot to observethe system output without diverting his attention when directed mostlyto the outside of the cockpit.

These and other objects of the invention are achieved by a head-up PWIdisplay unit consisting of a plurality of elongated light sources whichare attached about the windshield and the side windows. When one or moreof the light sources is illuminated, in response to the output of one ofthe detectors, the pilots peripheral vision enables him to notice theirillumination and direct his attention to the sector related to theilluminated light sources, while continuously directing his attention toevents outside the cockpit. By incorporating elongate rather than spotlight sources the pilot is provided with bearing boundaries of thesector to be searched. Such a novel display enables the pilot to locatean intruding target as soon as possible. It eliminates the disruption ofthe pilots attention from events outside of the cockpit as is the casein the prior art which require the pilot to observe a panel inside thecockpit and thereafter redirect his attention to the outside in thedirection of the particular sector in which the target has beendetected.

The novel features of the invention are the set forth with particularityin the appended claims. The invention will best be understood from thefollowing desc ription when read in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a projection of a windshieldand side window on an array of viewable sectors;

FIG. 2 is a diagram of detectors arranged in an arrangementcorresponding to the sectors array;

FIG. 3 is a diagram of light sources located about the windshield andthe side windows; and

FIG. 4 is a block diagram of circuitry for controlling the energizationof the light sources as a function of the outputs of the detectors.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Attention is now directed toFIG. 1 which is a projection of a windshield 11 and side windows 12 and13 of a cockpit on a plurality of detection sectors S,-S Sectors S andS, are areas viewable through window 12 while S and S are viewablethrough window 13. The rest of the sectors are viewable throughwindshield 11. The PWI system includes a plurality of detectorsdesignated D -D in FIG. 2. Each detector has a fixed field of view,e.g., 20 X 20, corresponding to one seetor and it provides an outputonly when it detects a target in its corresponding sector. As seen thedetectors are arranged to correspond to the array of the sectors shownin FIG. 1. Thus the combined detector array covers selected azimuth andelevation images about the aircrafts longitudinal axis, which herein isassumed to be perpendicular to FIGS. 1 or 2.

As previously pointed out, the desired display indicating which detectorprovides an output, i.e., in

which sector a target is detected, is one which provides such indicationwithout diverting the pilots attention from events outside the cockpit.Altemately stated, the display should be one which the pilot can noticewhile looking out through the windshield or one of the side windows. Inaccordance with the present invention a head-up display is provided. Itconsists of a plurality of light sources which are attached about thewindshield and the side windows. One or more of these sources areilluminated when a particular detector provides an output as will beexplained hereafter. The pilots peripheral vision, while looking out ofthe cockpit, is sufficient to notice which light source or sources areilluminated, so that the pilot can immediately visually scan theparticular sector in which a target is detected. Such a displayarrangement insures that the pilots attention is not diverted fromobserving events outside the cockpit while providing him with anindication of the sector in which a target is detected.

In one particular embodiment for an array of detectors as shown in FIG.2, 10 light sources are employed and are attached about the windshieldand the side windows as shown in FIG. 3, wherein the light sources arerepresented by rectangles L -L Sources L and L, are placed about window12 and L and L about window 13, while L L and L are placed above thewindshield l and L L and L below it or just above the panel board. Lightsource L which is located in the direction of sector S is illuminatedwherever a target is detected in S causing detector D to provide anoutput. Similarly sources L -L are illuminated whenever D D D D D D,,, DD and D provide outputs, respectively. When B, provides an output,indicating the detection of a target in 8,, both L and I. above andbelow sector 5., are illuminated. Similarly both L and L are illuminatedwhen a target is detected in sector 8-, and D provides an output, whileL and L,, are illuminated when D provides an output indicating targetdetection in sector S It should be appreciated that since the lightsources are placed in directions pointing to their correspondingsectors, once the pilot notices which sources are illuminated he knowsimmediately which sector should be visually scanned, and is able to doso without diverting his attention from observing events occurringoutside.

In accordance with the present invention the light sources areelongated, rather than spot sources. Thus, their lengths assist thepilot in determining the bearing boundaries of the sector to besearched. By enabling the pilot to determine the sectors bearingboundaries the search time is greatly reduced thereby enabling the pilotto locate the intruding target. Thus, the novel display provides thedesired advantages, discussed herebefore.

It should be apparent that various techniques may be used to control theenergization of sources L -L from an appropriate power source as afunction of the outputs of detectors D -D One simple arrangement isshown in FIG. 4 in which the power source is designated by numeral 20.Its output is shown connected to L -L through gates G -G respectively.Gates 6,, G G and G are opened or enabled by the direct outputs of D D Dand D respectively, while gates 6 -6 are opened or enabled by theoutputs of two-input OR gates 21-26. These gates are needed to insureproper energization of the sources L -L located above and below thewindshield as a function of the front sector in which a target isdetected.

It is generally desirable to use sources whose brightness can beadjusted as a function of the light intensity in the cockpit. In oneembodiment strips of a commercially available electroluminescent tapeare used as the light sources. Such tape, which has to be energized byan AC source, uses very little power. Another advantage of such tape isthat its brightness can be varied as a function of source frequency orvoltage. Thus by varying the frequency or voltage, the brightness can beadjusted as a function of cockpit light intensity. In the particularembodiment strips of Sylvania green Panelescent Tape-Lite were used. Thebrightness of this particular tape varries from 5 footlamberts at V 60Hz to 30 foot-lamberts at 120 V 40 Hz. Its power requirement isapproximately 0.3 watts per foot at 120 V, 60 Hz. This particular tapeis described as one example. It is apparent that other elongated meansmay be used as the elongated light sources, e.g., liquid crystals. Suchmeans may be preferrable under bright sky conditions if the strips arefound to provide insufficient brightness.

Although particular embodiments of the invention have been described andillustrated herein, it is recognized that modifications and variationsmay readily occur to those skilled in the art and consequently it isintended that the claims be interpreted to cover such modifications andequivalents.

What is claimed is:

1. For use with a system in an airborne airplane which includes an arrayof detectors for detecting targets located in azimuth and elevationranges with respect to said airplane, said ranges defining an array ofsectors corresponding to the array of said detectors with each detectorproviding an output when a target is detected by it in a sector which iswithin its field of view, said sectors being viewable by a pilot fromthe cockpit, having at least one window-like opening, a displaycomprising:

a plurality of elongated light sources each associated with at least onesector and secured adjacent said opening in the direction of the sectorwith which it is associated with the length of the source defining thebearing boundaries of the source with which the light source isassociated; and

means for illuminating at least one of said light sources when a targetis detected in the sector with which it is associated.

2. The arrangement as recited in claim 1 wherein said airplane includesa front window through which are viewable at least two sectors eachdefining two different elevation ranges, with at least one of said lightsources being secured above said front window and one of said lightsources being secured below said front window.

3. The arrangement as recited in claim 1 wherein said airplane includesa front window through which are viewable first, second and thirdsectors defining the same azimuth range and a first lower elevationrange, a second middle elevation range and a third upper elevationrange, a first light source secured to the top of said front window anda second light source secured below said front window at an azimuthcorresponding to the sectors azimuth range, said means energizing saidfirst light source when a target is detected in either said second andthird sectors and energizing said second light source when a target isdetected in either said first or said second sector.

4. In combination with a system in an airborne airplane which includesat least an array of detectors with a combined field of view coveringselected azimuth and elevation ranges, the field being divisable intocontiguous sectors viewable from the front window of the airplanescockpit with each detector being associated with a different sector andproviding an output when a target is detected in the sector associatedtherewith, a display comprising:

a plurality of energizable light sources secured above and below saidfront window, each associated with at least one of said sectors andsecured about said window at an elevation and azimuth corresponding tothe sectors elevation and azimuth ranges within said field of view; and

control means for utilizing the outputs of said detectors to energizethe light sources which are associated with the sectors from whichtargets are detected.

5. The arrangement as recited in claim 4 wherein said control meansinclude means for varying the brightness of the energized light sources.

6. The arrangement as recited in claim 4 wherein said array includes atleast first, second, third and fourth detectors arranged in a 2X2 array,respectively, responsive to targets detected in first, second, third andfourth sectors of said field of view, the first, second, third andfourth sectors defining upper left, lower left, upper right and lowerright quadrants of said field of view, and said display includes first,second, third and fourth light sources, with said first and second lightsources being secured above and below the left side of said window andsaid third and fourth light sources being secured above and below theright side of said window, and said control means utilize the outputs ofsaid detectors to energize the light source whose location relative tosaid window is in the direction of the sector in which a target isdetected.

1. For use with a system in an airborne airplane which includes an arrayof detectors for detecting targets located in azimuth and elevationranges with respect to said airplane, said ranges defining an array ofsectors corresponding to the array of said detectors with each detectorproviding an output when a target is detected by it in a sector which iswithin its field of view, said sectors being viewable by a pilot fromthe cockpit, having at least one window-like opening, a displaycomprising: a plurality of elongated light sources each associated withat least one sector and secured adjacent said opening in the directionof the sector with which it is associated with the length of the sourcedefining the bearing boundaries of the source with which the lightsource is associated; and means for illuminating at least one of saidlight sources when a target is detected in the sector with which it isassociated.
 2. The arrangement as recited in claim 1 wherein saidairplane includes a front window through which are viewable at least twosectors each defining two different elevation ranges, with at least oneof said light sources being secured above said front window and one ofsaid light sources being secured below said front window.
 3. Thearrangement as recited in claim 1 wherein said airplane includes a frontwindow through which are viewable first, second and third sectorsdefining the same azimuth range and a first lower elevation range, asecond middle elevation range and a third upper elevation range, a firstlight source secured to the top of said front window and a second lightsource secured below said front window at an azimuth corresponding tothe sectors'' azimuth range, said means energizing said first lightsource when a target is detected in either said second and third sectorsand energizing said second light source when a target is detected ineither said first or said second sector.
 4. In combination with a systemin an airborne airplane which includes at least an array of detectorswith a combined field of view covering selected azimuth and elevationranges, the fielD being divisable into contiguous sectors viewable fromthe front window of the airplane''s cockpit with each detector beingassociated with a different sector and providing an output when a targetis detected in the sector associated therewith, a display comprising: aplurality of energizable light sources secured above and below saidfront window, each associated with at least one of said sectors andsecured about said window at an elevation and azimuth corresponding tothe sector''s elevation and azimuth ranges within said field of view;and control means for utilizing the outputs of said detectors toenergize the light sources which are associated with the sectors fromwhich targets are detected.
 5. The arrangement as recited in claim 4wherein said control means include means for varying the brightness ofthe energized light sources.
 6. The arrangement as recited in claim 4wherein said array includes at least first, second, third and fourthdetectors arranged in a 2 X 2 array, respectively, responsive to targetsdetected in first, second, third and fourth sectors of said field ofview, the first, second, third and fourth sectors defining upper left,lower left, upper right and lower right quadrants of said field of view,and said display includes first, second, third and fourth light sources,with said first and second light sources being secured above and belowthe left side of said window and said third and fourth light sourcesbeing secured above and below the right side of said window, and saidcontrol means utilize the outputs of said detectors to energize thelight source whose location relative to said window is in the directionof the sector in which a target is detected.